Stabilization of chlorinated hydrocarbons



3,070,635 STABlLIZATiON F CHLOREWATED HYDROCARBONS George Davidowich, Bayonne, and Morton W. Leeds,

Murray Hill, N..l., assignors to Air Reduction Cornpany, Incorporated, New York, N.Y., a corporation of New York No Drawing. Filed Jan. 18, 1961, Ser. No. 83,392 3 Claims. (Cl. 260-6525) This invention relates to the stabilization of chlorinated hydrocarbons. More particularly this invention relates to novel stabilized chlorinated hydrocarbon compositions and to processes for producing the same.

Chlorinated hydrocarbons are widely used as solvents for a variety of purposes such as degreasing metal articles, dry cleaning, and extraction of caffeine from coffee. A serious drawback encountered in their use is their tendency to undergo degradation by oxidation, hydrolysis or pyrolysis on exposure to light, air, heat, moisture or metal surfaces.

Various stabilizers have been used to retard the decomposition of chlorinated hydrocarbons. Many of these stabilizers substantially reduce the rate of decomposition and are satisfactory for some purposes. However, new and improved stabilizers are constantly being sought to meet the expanding needs for chlorinated hydrocarbon solvents which are stable under diverse conditions.

A primary object of the present invention is to provide novel stabilized chlorinated hydrocarbon compositions.

A further object of this invention is the use of a synergistic combination of two stabilizers to effect a substantially greater degree of stabilization than is obtainable with either stabilizer alone.

In accordance with the present invention it has been found that chlorinated hydrocarbons can be stabilized with small amounts of a mixture of a compound having the general formula where R is selected from the group consisting of alkyl radicals containing from 1 to about carbon atoms, cycloalkyl radicals containing from 3 to about 8 carbon atoms, monocyclic aryl radicals containing from 6 to about 10 carbon atoms (e.g., phenyl, p-tolyl), R is a lower alkyl radical containing from 1 to about 4 carbon atoms, and R is selected from the group consisting of hydrogen and lower alkyl radicals containing from 1 to about 3 carbon atoms, and R and R together with the adjoining carbon atom form a cycloalkyl radical contain ing from 3 to about 8 carbon atoms, and a second stabilizing compound selected from the group consisting of 1,4-dioxane and compounds having the formula where R, is selected from the group consisting of alkyl radicals containing from 1 to about 10 carbon atoms, cycloalkyl radicals containing from 3 to about 8 carbon atoms, monocyclic aryl radicals containing from 6 to about 10 carbon atoms (e.g., phenyl, p-tolyl), R is a ower alkyl radical containing from 1 to about 4 carbon toms, and R is selected from the group consisting of 3,070,635 Patented Dec. 25, 1962 hydrogen and lower alkyl radicals containing from 1 to about 3 carbon atoms, and R and R together with the adjoining carbon atom form a cycloalkyl radical containing from 3 to about 8 carbon atoms. Typical ketone stabilizers include 3-methyl-3-formyloxy-2-butanone, 3- rnethyl-3-acetoxy-2-butanone, 3-phenyl-3-acetoxy-2-buta none, 3-p-tolyl-3-acetoxy-2-butanone, 3-methyl-3-acetoxy- 2-pentanone, 3-ethyl-3-acetoxy-2-pentanone, and 3-methyl 3-acetoxy-2-dodecanone; 3-methyl-3-acetoxy-2-butanone is preferred. Among the suitable acetylenic ester stabilizers are 3-methyl-3-formyloxy-l-butyne, 3-methyl-3-acetoXy-1- butyne, 3-phenyl-3-acetoxy-l-butyne, 3-p-tolyl-3-acetoxyl-butyne, 3-metl1yl-3-acetoxy-l-pentyne, and 3-methy'l-3- acetoxy-ldodecyne; preferred stabilizers are 3-methyl- 3 acetoxy 1 butyne and 3-methyl-3-acetoxy-l-pentyne. While some stabilization is achieved by the use of any one of these compounds alone, the stabilization obtained with two compounds according to this invention is considerably greater than the additive effects of the two stabilizers. Effective stabilization according to this invention is achieved by adding from about 0.1 to about 0.5 percent by volume of 3-methyl-3-acetoxy-2-butanone and from about 0.1 to about 0.5 percent by volume of a compound selected from the group consisting of 1,4-dioxane, Z-rne'thyl-3-butyn-2-ol acetate, and 3-methyl-l-phentyn-3-ol acetate to the chlorinated hydrocarbon to be stabilized. The synergistic effect of two stabilizers is especially pronounced in chlorinated hydrocarbon solutions containing approximately equal volumes of the two stabilizers. However, the ratio of the two stabilizers can be varied over wide limits, as will be apparent to those skilled in the art, provided the maximum and minimum concentrations of each stabilizer are within the limits set forth above.

The chlorinated hydrocarbon to be stabilized may be any one of the lower molecular weight chlorinated hydrocarbons such as carbon tetrachloride, chlor'oforin', t'r'ichloroethylene, perchloroethylene, ethylene dichloride, 1,3-dichloropropane, and the like. 7

The marked effectiveness of the synergistic combinations of the present invention is illustrated by the following example.

EXAMPLE 1 In all of the stability tests described herein, the stability is determined according to the following procedure:

One hundred ml. of carbon tetrachloride having a statbilizer content as indicated in Table I below is placed in a ml. Erlenmeyer flask fitted with an air condenser. To the flask is added an aluminum strip 2" x /2" which has been scratched five times on each side with scissors. The solution is refluxed for approximately 8 hours and allowed to stand at room temperature for approximately 16 hours each day for the duration of the test. Except as otherwise indicated, the test is terminated when corrosion of the aluminum test specimen is observed. The reflux times are indicated in Table I below.

Solutions 1 to 4, inclusive, represent solutions stabilized with two stabilizers according to the present invention. Solutions 5 to 11, inclusive, are given for purposes of comparison to show the stability of unstabilized carbon tetrachloride and of carbon tetrachloride stabilized with only a single stabilizer in the same test procedure.

Table I below shows the results obtained in each of the stabilization tests carried out according to the foregoing procedure. The solutions are observed to be a light straw color and the aluminum specimens show signs of attack, indicating slight decomposition at the end of the test, except as otherwise noted.

Table 1 Run Stabilizing agent Percent by Run Percent Reflux volume No. Stabilizing agent by time,

volume hours 16..... 3-meth3il-3-iormy1oxy-2-butanone 0.2

p us 3-methyl-3-propi0n0xy-l-butyne 0.1 8 g fi acetoxy 2 butanone 1 46 17-.." B-methyl-3-proplonoxy-2-butanone 0.2

1,4-di0xane 0, 1 p us 3-n1ethyl-3-acetoxy-l-hexyne 0.2 3 2 5 acetoxy 2 butamme' 2 1 31 18.-." 8-methyl-B-acet0xy-2-butanone. 0.2

1,4-dioxane 0. 2 p us 10 3-methyl-3-acetoxy-1-decync 0.3 3 2 2 acetoxy 2 butanone' 1 49 10-.- H-methyl-Zl-acetoxy-Z-butanone 0.2

3-methyl-3-acctoxy-l-butyne 0.1 P

3-phenyl-3-acetoxyJ-butyne 0.2 3 g g acetoxy zbutanone 131 20. 3-phen3il-3-acetoxy-2-butanone 0.2 3-methyl-3-acetoxy-1-butyne.. 0.2 P us v 3-phenyl-3-acet0xy-1-butyne. 0.2 22:: 'f f %g 3 acetoxy butanon g 21-.- 8-ethyl-13-acetoxy-Z-pentanone. 0.2

1;) us g 3-p-tolyl-3-acetoxy-1-pentyne 0.2 1 2 22 3-methyl-3-acctoxy-2-deoanone. 0.2

' p us 2 g 3-methyl-3-acetoxy-l-butyne...- 0. 2 23 3-cycloliexyl-3-acet0xy2-butano 0.2

p US 1 Solution clear specimen not attacked at end of test. 3'cydohexyl'aacetoxy'l'butyne-- 2 1 Solution highly colored, specimen showed considerable corrosion. sacetoxycyclohexyl kem There is no apparent decomposition in runs 2 and 4 05 gfi jggggylgfiiggggg 8; above, as indicated by clear solutions and absence of any p 51... y

1 4-dioxane 0. 2 on the alummum specimens at h egd the re 26-.." 3 methyl-3-acetox dodecanone. 0.2 spective tests. The same stabihzer cornbmatlons in lower 20 plus concentrations imparted stability over long periods of time 1144mm 2 in runs 1 and 3. Much shorter periods of stabilization are observed in carbon tetrachloride solutions containing only a Single stabilizer in runs 5 to 10 For example deconb The resulting solutions are stable against decomposition 7 position of carbon tetrachloride containing 0.1 percent by 3 at both room temperature and elevated temperatures volume of B-methyl-S-acetoxy-2-butanone plus 0.1 percent by volume of 1,4-dioxane is observed only after 46 hours .of refluxing. In contrast, decomposition of carbon tetrachloride stabilized with 0.1 percent by volume of B-methyl- .3-acetoxy-2-butanone alone is observed after only 2 hours, and decomposition of carbon tetrachloride stabilized with 0.1 percent by volume of 1,4-dioxane is observed after 5 hours.

EXAMPLE 2 Carbon tetrachloride is stabilized with a pair of stabilizing agents as indicated in Table II below:

While the foregoing invention has been described with reference to specific embodiments thereof, it is understood that the scope of this invention is to be measured only by the scope of the appended claims.

We claim:

1. A composition of matter comprising carbon tetrachloride and small but stabilizing amounts of 3-methyl-3- acetoxy-Z-butanone and a compound selected from the group consisting of 1,4-dioxane and 3-methyl-3-acetoxy- 1-butyne.

2. A composition of matter comprising carbon tetrachloride and small but stabilizing amounts of 3-methyl-3 acetoxy-Z-but'anone and 1,4-dioxane.

3. A composition of matter comprising carbon tetrachloride and small but stabilizing amounts of 3-methyl- 3-acetoxy-2-butanone and 3-methyl-3-acetoxy-l-butyne,

References Cited in the file of this patent UNITED STATES PATENTS 2,298,638 Prutton Oct. 13, 1942 2,811,252 Bachtel Oct. 29, 1957 FOREIGN PATENTS 579,462 Canada July 14, 1959 

1. A COMPOSITION OF MATTER COMPRISING CARBON TETRACHLORIDE AND SMALL BUT STABILIZING AMOUNTS OF 3-METHYL-3ACETOXY-2-BUTANONE AND A COMPOUND SELECTED FROM THE GROUP CONSISTING OF 1,4-DIOXANE AND 3-METHYL-3-ACETOXY1-BUTYNE. 